CSP Systems and Fossil Backup

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Paul Gilman
CSP Systems and Fossil Backup

Question

I’m trying to use the SAM tool for CSP towers. I’m using the version 2012.5.11. I see there are entries for fossil fuel backup costs in both the fixed and variable sections of the tab “Total System Costs”, but I don’t know how to add a 15% fossil fuel addition to my 100MWe CSP plant to augment the power production and decrease the LCOE.

Is there a section where I can add the 15% ? I’ve looked at all the tabs, including “Power cycle” and I just don’t see it. Am I missing something?

Any help you could provide would be most beneficial.

Answer

The Fossil Backup cost on the System Costs page under Direct Capital is in $ per MW of power cycle nameplate capacity and is for costs associated with installing the fossil backup system.

The Fossil Fuel Cost under Operation and Maintenance Costs is in $/MMBTU of fuel consumed by the fossil backup system and is the cost of fuel.

You specify how the fossil backup system operates on the Thermal Storage page (under Thermal Storage Dispatch Control) by assigning a Fossil Fill Fraction to each of up to nine dispatch periods, and defining when the periods apply in the weekday and weekend schedule matrices. Please see the Thermal Storage help topic for more details.

Unfortunately, it is not possible to directly specify a fossil fill percentage as you describe. You can experiment with different fossil fill fractions and dispatch schedule to find the combination that results in the desired percentage.

Best regards,
Paul.

Paul Gilman

The following document explains the dispatch control variables for the CSP thermal storage model with examples of different control scenarios:

CSP Storage Dispatch Control (PDF 157 KB)

Best regards,
Paul.

Vahan Poghosyan
Vahan Poghosyan's picture

Dear Paul,
For physical trough model, if I give Fossil Fill Fraction a value of for instance 0.5 fossil fuel heaters work when supplied thermal energy from field and storage is not enough to maintain the 50% of design energy, does it mean that fossil fuel heaters also work at night time?
Is it possible to distinguish from results which portion of generated electricity was generated from fossil fuel and which from pure solar?
Best Regards
Vahan

Vahan Poghosyan
Vahan Poghosyan's picture

Dear Paul,
sorry, the first question is wrong. Please answer only the second question, Is it possible to distinguish from results which portion of generated electricity was generated from fossil fuel and which from pure solar?
Best Regards
Vahan

Paul Gilman

Dear Vahan,

Yes. SAM's physical trough model reports the energy required for fossil backup in the hourly results as "Auxiliary heater operation parasitic load (MWh)."

Best regards,
Paul.

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